1. Field of the Invention
This invention relates to balloon or Foley type retention catheters. More particularly this invention relates to an all plastic catheter having a thermosetting polyurethane balloon, and further to a method for sealing the balloon to a thermoplastic polyurethane catheter body.
2. Description of Prior Art
Retention type catheters have been in use for many years and traditionally comprise a flexible and resilient tubular body portion having elongated drainage and inflating lumens extending longitudinally therethrough. An opening is provided in the catheter wall extending into communication with the inflating lumen and an inflatable sack or balloon is secured to the catheter over the opening whereupon introduction of fluid pressure through the inflating lumen will cause the sack or balloon to distend. The distal end of the catheter adapted for insertion into the patient is normally closed off and rounded and drainage eyes are provided in the catheter wall in communication with the drainage lumen, said eyes being located intermediate the balloon and the catheter distal end. At the opposite proximal end of the catheter, funnel portions are provided in communication with the inflating and drainage lumens, respectively, the tubular body normally being bifurcated adjacent its proximal end, whereupon the proximal ends of the inflating ends drainage lumen extend angularly from each other. Catheters of this general type are illustrated in U.S. Pat. Nos. 2,248,934 and 2,308,404.
Although catheters of the general type described supra have been conventionally made of rubber, recent developments have been directed toward the fabrication of all plastic catheters which reportedly show less tendency for the formation of undesirable calcium or other salts in the drainage lumen, and which have a high degree of biocompatibility. Such all-plastic catheters are described for example in U.S. Pat. Nos. 3,392,627, 3,528,869 and 3,539,674.
Typical plastic materials which have been utilized in the fabrication of catheters include polyurethane, polyvinyl chloride and copolymers of vinyl chloride with vinyl acetate or ethylene. Particularly preferred compositions for catheter bodies are the elastomeric grades of polyurethane such as Estane polyester-polyurethane of the B. F. Goodrich Chemical Company. Balloons of thermoplastic polyurethanes however, have been found to require higher inflation pressures than conventional latex balloons and to take a permanent set after prolonged inflation possibly causing trauma to the patient upon withdrawal. As a result, it has been suggested to use latex balloons with polyurethane catheter bodies as in U.S. Pat. Nos. 3,112,748 and 3,850,720. In such constructions the latex balloons may be Teflon-coated to render them less irritating to the patient while largely preserving the desirable balloon inflation/deflation properties of latex. Even Teflon coating, however, does not completely eliminate tissue reaction to the latex material.
It is accordingly an object of the present invention to provide an all plastic catheter having improved inflation/deflation properties. It is a further object of this invention to provide an all plastic catheter having a thermosetting polyurethane balloon member. A yet further object of this invention is to provide a method for securely attaching a thermosetting polyurethane balloon to a thermoplastic polyurethane catheter body. Yet other objects of the invention will be apparent from the ensuing descriptions and examples.